#include <iostream>
using namespace std;
long long a, b, n,ans;
int main()
{
	cin >> a >> b >> n;
	long long sum = a * 5 + b * 2;
	if (sum <= n)
	{
		long long count = 0;
		for (long long i = 1; i <= 7; i++)
		{
			if (i <= 5)
			{
				count += a;
				if (count >= n)
				{
					cout << i << endl;
					break;
				}
			}
			else
			{
				count += b;
				if (count >= n)
				{
					cout << i << endl;
					break;
				}
			}
		}
	}
	else
	{
		long long c = n / sum;
		long long d = n % sum;
		long long count = 0;
		for (long long i = 1; i <= 7; i++)
		{
			if (i <= 5)
			{
				count += a;
				if (count >= d)
				{
					cout << i+c << endl;
					break;
				}
			}
			else
			{
				count += b;
				if (count >= d)
				{
					cout << i+c << endl;
					break;
				}
			}
		}
	}
	return 0;
}